1. Field of the Invention
Embodiments of the present invention generally relate to an apparatus and method for transferring substrates in a processing system. More specifically, embodiments of the present invention relate to a blade, for use with high temperature processes, designed to reduce thermal stress on a substrate.
2. Description of the Related Art
The effectiveness of a substrate fabrication process is often measured by two related and important factors, which are device yield and the cost of ownership (CoO). These factors are important since they directly affect the cost to produce an electronic device and thus a device manufacturer's competitiveness in the market place. The CoO, while affected by a number of factors, is greatly affected by the system and chamber throughput, or simply the number of substrates per hour processed using a desired processing sequence. In an effort to reduce CoO, electronic device manufacturers often spend a large amount of time trying to enhance the process sequence and chamber processing time to achieve the greatest substrate throughput possible given the cluster tool architecture limitations and the chamber processing times. A significant portion of the time it takes to complete the processing sequence is taken up transferring the substrates between the various processing chambers.
Semiconductor processing systems typically integrate a number of process chambers on a single platform to perform several sequential processing steps without removing the substrate from a highly controlled processing environment. Once the cluster tool has been configured with the requisite number of chambers and auxiliary equipment for performing certain process steps, the system will typically process a large number of substrates by moving the substrates through the chambers using a robot disposed in the system. The robot provides both lateral and rotational movement of a substrate on a robot blade to retrieve, transfer, and deliver substrates from one location within the system to another location. Current practice also includes the use of robot arms to transfer substrates from a loading port into various processing chambers within a multiple chamber processing system. FIG. 1 illustrates a prior art blade 100 which is currently used for extracting substrates from processing chambers. The blade 100 has a generally flat blade surface 110 defined on either side by a first lateral shoulder 120 and a second lateral shoulder 130. The flat blade surface 110 generally supports the substrate.
Current processing recipes often require exposing the substrate to processing temperatures well in excess of 550° C. in specified process chambers. After processing, the hot substrate is extracted from the processing chamber and placed in a cooling station. However, extracting the hot substrate from the process chamber and exposing the hot substrate to a much cooler atmosphere has resulted in several problems including substrate breakage, warping, and other defects. As shown in FIG. 2, the prior art blade design of FIG. 1 places a significant amount of thermal stress on the substrate. The significant amount of material of the flat blade surface 110 under the hot substrate slows the cooling of the substrate and the prior art blade 100. As a result, current extraction temperatures are limited to 550° C. and the corresponding substrate throughput is limited because the substrate and blade must cool from the processing temperate to a minimum of 550° C. before the substrate and blade can be removed from the processing chamber.
Therefore, there is a need for a blade that allows for extraction temperatures greater than 550° C. while reducing incidences of substrate breakage and warping.